Spiral wound abrasive belt and method

ABSTRACT

A spiral wound abrasive belt is formed from an abrasive media including a plurality of webs. The webs of the abrasive media may include coated abrasives joined by splicing media or other suitable joining material. Alternatively, the webs may include individual single or multiple layers that form a coated abrasive simultaneously along with the spiral belt without the use of additional joining material. A method of forming the spiral belt includes draping the abrasive media over a fixed hub at an angle to form the spiral belt while abutting the edges of the outermost web and overlapping the outermost web and adjacent web or webs. Heat and pressure may be applied to the joined edges to form a strong bond along the spiral seam. Another method includes introducing the webs forming the abrasive media at an angle and draping the webs over a fixed hub. The abrasive media may then be passed around an adjustable hub that provides tension in the spiral belt while allowing for different circumferentially sized belts. Continuous feeding of the input abrasive media or webs will result in a spiral belt of ever increasing width that may subsequently be slit to a desired width.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of U.S. Ser. No. 09/598178,filed Jun. 21, 2000, pending, the disclosure of which is hereinincorporated by reference.

FIELD OF THE INVENTION

[0002] This invention relates to spiral wound abrasive belts, andmethods and apparatus for making the same.

BACKGROUND OF THE INVENTION

[0003] Endless coated abrasive articles, such as belts, sleeves, tubesand the like, are used in a variety of abrading operations, especiallyin the woodworking and metal finishing industries. These operationsrequire that the articles be made and supplied by the coated abrasivemanufacturer in a large variety of widths and circumferences.

[0004] Standard belt forming techniques provide coated abrasive belts inwidths equal to the widths of the coated abrasive materials from whichthey are formed. Typically, a piece of coated abrasive material, equalin width to the desired belt width, is cut at a suitable angle acrossits width. The piece of material is then measured to a length equal tothe desired belt circumference plus an allowance for forming a lapjoint, if desired. A second cut across the width is then made at thesame angle as the first cut. An adhesive composition is then applied toone or both ends and the ends are joined by overlapping, causing theends to adhere to one another by means well known to those skilled inthe art.

[0005] Alternatively, the piece of coated abrasive material may be cutto a length without an allowance for a lap joint. In this situation, theends of the material are butted and joined to one another with anoverlapping reinforcing flexible patch suitably adhered to the backsideof the two ends of the material.

[0006] Another alternative method for making a coated abrasive belt isdisclosed in European Patent Application. No. 0497451, published Aug. 5,1992, wherein the method provides a coated abrasive belt that includesan abrasive layer bonded to a flexible backing material, which in turnincludes a flexible support and a layer of hot-melt adhesive. A buttjoint is formed at the ends of a strip of the material with heat andpressure added to cause the hot-melt adhesive to flow across the joint.

[0007] Coated abrasive belts in widths greater than the width of thecoated abrasive material have been produced by a number of methods. Onesuch method involves piecing together segments of coated abrasivematerial to form wide, multi-jointed sectional belts that cover a broadrange of belt widths and belt circumferences. These belts, however, havethe drawback of increased cost due to the multiple piecing and joiningprocesses required to fabricate the belts. In addition, multiple jointsincrease the potential for problems due to weakening of the belt at thejoints, as well as process control and quality issues.

[0008] Another method of forming an endless coated abrasive belt thathas a width greater than the width of coated abrasive material fromwhich it was made involves spiral winding of material. A conventionalmethod for making such “spiral wound” belts involves winding an innerliner spirally on a mandrel having an outer circumference equal to theinside circumference of the desired abrasive belt, applying an adhesiveto the outer surface of the inner liner, and winding spirally over theadhesive layer a strip of coated abrasive material. Such a method iswidely used for the fabrication of belts in smaller sizes, up to, forexample, 6 inches in diameter or 19 inches in circumference.

[0009] Another such method involves spiral winding narrow strips ofcoated abrasive material having scarfed (or angle cut) edges thatoverlap and are adhered using conventional techniques. Alternatively,the edges of a piece of wider coated abrasive material may be formed toabut when wound spirally within a revolvable drum. Subsequently, aresinous coating material is applied to the inner periphery of the beltwhich then spreads, as the drum revolves, to form a continuous layer ofresinous coating that joins the belt material together. Yet anothermethod involves spiral winding about a mandrel a coated abrasivematerial with abutting edges that has a flexible backing materialincluding a layer of hot-melt adhesive. The spiral wound material isthen heated to cause the hot-melt adhesive to flow across the abuttededges resulting in a continuous layer that secures the edges together.

[0010] There are numerous shortfalls in the methods described above. Useof a fixed mandrel or drum limits the belts formed on such mandrel ordrum to a single diameter. Use of thinner material with these methodsmakes it difficult to line up the seams and traditional cloth abrasivemedia may have baggy edges that form puckers or uneven seams in thebelt, both of which can cause processing and belt performance problemslater on. These methods are usable to form belts one at a time, makingthem inefficient, less productive and more expensive. In addition, thetypes of abrasive materials usable with these methods are not typicallysufficiently reinforced, such that the resulting abrasive belts tend todelaminate at the seams or during use over time.

[0011] An ongoing need exists for spiral wound abrasive belts that areproduced in a faster, cheaper and more efficient manner, and in avariety of sizes. Such spiral wound belts that take advantage ofabrasive media constructions that produce stronger and more durableabrasive articles are also desirable.

SUMMARY OF THE INVENTION

[0012] The present invention is a spiral wound abrasive belt formed froman abrasive media including a plurality of webs, and a method andapparatus for constructing the same. The webs of the abrasive media mayinclude coated abrasives joined by splicing media or other suitablejoining material. Alternatively, the webs may include individual singleor multiple layers that form a coated abrasive simultaneously along withthe spiral belt without the use of additional joining material.

[0013] In one embodiment, the abrasive media may be draped over a fixedhub at an angle to form the spiral belt while abutting the inner edge ofthe spirally wrapped web with the outer edge of the succeeding wrap ofweb. Heat and pressure may be applied to the joined edges to form astrong bond along the spiral seam. In another embodiment, the websforming the abrasive media may be introduced at an angle and draped overa fixed hub. The abrasive media may then be passed around an adjustablehub that provides tension in the spiral belt while allowing fordifferent circumferentially sized belts. Continuous feeding of the inputabrasive media or webs will result in a spiral belt of ever increasingwidth that may subsequently be slit to a desired width. Optionally, anoutermost web positioning system, including sensors, a controller and aweb positioning mechanism may be provided to minimize gaps or overlapsalong the spiral seam.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0014]FIG. 1 is a perspective view of one embodiment of a spiral woundabrasive belt formed in accordance with the present invention.

[0015]FIG. 2 is a plan view of an abrasive media including two webs foruse in the formation of the spiral wound abrasive belt of FIG. 1.

[0016]FIG. 3 is a partial cross-sectional view of the spiral woundabrasive belt of FIG. 1.

[0017]FIG. 4 is a partial cross-sectional view of a second embodiment ofa spiral wound abrasive belt formed from an abrasive media includingthree webs.

[0018]FIG. 5 is a partial cross-sectional view of a third embodiment ofa spiral wound abrasive belt formed from an abrasive media including twowebs.

[0019]FIG. 6 is a partial cross-sectional view of a fourth embodiment ofa spiral wound abrasive belt formed from an abrasive media includingthree webs.

[0020]FIG. 7 is a perspective view of one embodiment of a spiral woundabrasive belt forming apparatus.

[0021]FIG. 8 is a partial end view of the apparatus of FIG. 7.

[0022]FIG. 9 is a schematic illustration of another embodiment of aspiral wound abrasive forming apparatus.

[0023]FIG. 10 is a diagram illustrating yet another embodiment of aspiral wound abrasive forming apparatus.

DETAILED DESCRIPTION OF THE INVENTION

[0024] With reference to the attached Figures, it is to be understoodthat like components are labeled with like numerals throughout theseveral Figures. FIG. 1 is a spiral abrasive belt 100 formed inaccordance with the present invention for use on a polisher, sander,grinder or other rotating machine using an abrasive surface. The spiralbelt 100 has a width 102 and a circumference 103. The spiral belt 100also has first and second belt ends 104 and 105, respectively, an innersurface 108 and an outer surface 110. The inner and outer surfaces 108,110 are preferably continuous such that there is no appreciablebeginning or end to the belt 100 while it rotates over a surface beingprocessed.

[0025]FIG. 2 is an abrasive media 80 that may be used to form the spiralbelt 100, in accordance with the present invention. The abrasive media80 includes a first web 50 having a width 56, and first and second sideedges 52 and 54, respectively, along the web length. The first andsecond side edges 52, 54 are preferably parallel to one another. In thisembodiment, the abrasive media 80 also includes a second web 60 that hasa width 68 and parallel first and second side edges 62 and 64,respectively. The first web 50 overlaps a first portion 65 of the secondweb 60 along the length leaving a second portion 66 of the second web 60exposed. As shown, the second portion 66 is sized to be about one-halfthe width 68 of the second web 60, although it may be smaller or largerif desired.

[0026] The abrasive media 80 has a first end 82 formed or cut at anangle 84 to the web side edges 52, 54, 62, 64. The angle 84 and thus thelength 86 of the first end 82 may vary depending on the desireddimensions of the spiral belt 100. In one embodiment, the first endlength 86 determines the circumference 103 of the spiral belt 100, sothat changes in angle 84 and length 86 will provide larger or smallerbelts as desired for a particular application. In another embodiment, apre-cut angled edge 84 is not required. The resulting spiral belt 100may be trimmed as needed to provide an even first belt end 104. In thisembodiment, the angle of winding and width 56 of the first web 50 (asdiscussed in more detail below) determine the resulting circumference103 of the spiral belt 100.

[0027] The abrasive media 80 may be configured as a continuous web,thereby forming a spiral belt 100 of ever increasing width, which maythen be slit to a desired belt width 102. Alternatively, the abrasivemedia 80 may be configured to include a second end 88, as shown in FIG.1, formed parallel to the first end 82, giving the abrasive media 80 afixed length (not shown). The length of the abrasive media 80 thendetermines the width 102 of the spiral belt 100.

[0028] The spiral belt 100 is formed by winding the abrasive media 80 ina spiral wherein side edge 52 is brought into abutting contact with sideedge 54, such that no gap is present. The angle 84 sets the angle ofwrap for the spiral belt 100. The angled first end 82 provides astarting point at first tip 83 for the spiral belt 100, as well as therelatively even first belt end 104. In a like manner, the angled secondend 88 provides an end point at tip 89 for the spiral belt 100 andsecond belt end 105 that is also relatively even. The resulting spiralbelt 100 has width 102. The first and second belt ends 104, 105 are bothpreferably configured to be generally perpendicular to the widthdimension 102 and generally parallel to each other. For continuous widthbelts, the second belt end 105 may be formed by slitting the belt 100 atthe desired width 102, instead of by a second end 88. Tabs 109 may beprovided to secure the angled first and second end tips 83 and 89 to theremainder of the spiral belt 100.

[0029] As the abrasive media 80 winds to form the spiral belt 100, thefirst web 50 overlaps the exposed second portion 66 of the second web60. FIG. 3 is a partial cross-sectional view of wound spiral belt 100showing the resulting relationship between the first and second webs 50and 60, respectively. In one embodiment, the second web 60 preferablyincludes an adhesive over the second portion 66, which facilitatesjoining with the first web 50 during winding to produce the spiral belt100.

[0030] The second web 60 may be provided as a narrow strip whose width68 is appreciably narrower than width 56 of the first web 50, as shownin FIGS. 2 and 3, functioning primarily for the purpose of joining theabutting edges 52 and 54 of the first web 50. As shown in FIG. 4 in asecond embodiment of a spiral belt 100′ formed from an abrasive media80′, a second web 60′ may alternatively be provided in a larger width68′ up to and including a width 56′ of a first web 50′, positioned anoffset amount 66′ from the first web 50′. As shown, the offset amount66′ is substantially less than one-half the width 68′ of the second web60′, however it may be smaller or larger if desired. The second webwidth 68′ should be no greater than the first web width 56′ or elsefirst web edges 52′ and 54′ will not abut, but will have a gap betweenthem. Alternatively, if the edges 52′, 54′ did abut without a gap, therewould be a bump running around the belt 100′ where the second web 60′overlaps itself. When the second web width 68′ is about equal to thefirst web width 56′, the second web side edges 62′ and 64′ will alsoabut without an appreciable gap in a manner similar to the side edges52′, 54′ of the first web 50′. In this embodiment, the second web 60′also preferably includes adhesive over the offset portion 66′ (appliedto either the first or second webs 50′, 60′) to facilitate joining ofthe second web 60′ to the first web 50′.

[0031] Although shown with two webs 50, 60 in FIGS. 1-3, and webs 50′and 60′ in FIG. 4, the spiral belt 100, 100′ may be formed from more orless webs as needed to produce a spiral belt 100, 100′ having thedesired properties for a particular application. In FIG. 5, a thirdembodiment of a spiral belt 120, shown in a cross-sectional view, isformed from an abrasive media 122 including three webs: a first web 125,a second web 130 and a third web 135. In this embodiment, the second web130 is somewhat narrower than the first web 125 such that the second web130 is undercut from first web edges 126, 127 leaving a gap 131 adjacentthe seam 128 where the edges 126, 127 abut. The third web 135 is thenpositioned within the gap 131, adjacent the first web 125 and offsetfrom one of the edges 126, 127 a portion 136, such that the third web135 overlaps and joins the seam 128 when the abrasive media 122 isspirally wound into the belt 120. In this embodiment, the second web 130may be attached to the first web 125 using many methods, including butnot limited to adhesive. The third web 135 preferably includes adhesiveat the offset portion 136 (applied to either the first or third webs,125, 135, respectively) to join the seam 128 of the belt 120.

[0032] Preferred adhesives include phenolic resins, aminoplast resins,hot melt resins, latex resins, epoxy resins, ethylene acrylic acidresins, polyvinyl acetate resins, radiation curable resins, urethaneresins, and pressure sensitive adhesives.

[0033] Adhesives preferably are thermosetting resins. The terms“thermosetting” or “thermoset” refer to reactive systems thatirreversibly cures upon application of heat and/or other energy sources,such as E-beam, ultraviolet radiation, visible light, etc., or with timeupon the addition of a chemical catalyst, moisture, or the like. Theterm “reactive” includes components that react with each other (or selfreact) either by polymerizing, crosslinking, or both. These componentsare often referred to as resins. The term “resin” refers to polydispersesystems containing monomers, oligomers, polymers, or combinationsthereof.

[0034] Phenolic resins may be used because of their thermal properties,availability, cost and ease of handling. There are two types of phenolicresins, resole and novolac. Resole phenolic resins have a molar ratio offormaldehyde to phenol, of greater than or equal to one to one,typically between 1.5:1.0 to 3.0:1.0. Novolac resins have a molar ratioof formaldehyde to phenol, of less than one to one.

[0035] Suitable phenolic resins preferably include about 70% to about85% solids, and more preferably about 72% to about 82% solids. Theremainder of the phenolic resin is preferably water with substantiallyno organic solvent due to environmental concerns. If the percent solidsis very low, more energy is required to remove the water and/or solvent.If the percent solids is very high, the viscosity of the resultingphenolic resin is too high which may lead to processing problems.

[0036] Examples of commercially available phenolic resins include thoseknown under the trade designations “VARCUM” and “DUREZ” from OccidentalChemical Corp., Tonawanda, N.Y.; “AROFENE” and “AROTAP” from AshlandChemical Company, Columbus, Ohio; “RESINOX” from Monsanto, St. Louis,Mo.; and “BAKELITE” from Union Carbide, Danbury, Conn.

[0037] Modified phenolic resins may also be used. For example, aplasticizer, latex resin, or reactive diluent may be added to a phenolicresin to modify flexibility and/or hardness of the cured phenolicbinder.

[0038] A suitable aminoplast resin has at least one pendantα,β-unsaturated carbonyl groups per molecule. These unsaturated carbonylgroups may be acrylate, methacrylate or acrylamide type groups. Examplesof such materials include N-hydroxymethyl-acrylamide,N,N′-oxydimethylenebisacrylamide, ortho and para acrylamidomethylatedphenol, acrylamidomethylated phenolic novolac and combinations thereof.

[0039] Suitable epoxide resins include monomeric epoxy resins andpolymeric epoxy resins. These resins can vary greatly in the nature oftheir backbones and substituent groups. Examples of epoxy resins include2,2-bis[4-(2,3-epoxypropoxyphenol)propane (diglycidyl ether of bisphenolA)] and commercially available materials under the trade designations,“EPON 828,” “EPON 1004,” and “EPON 1001F,” available from Shell ChemicalCo., Houston, Tex.; “DER-331,” “DER-332,” and “DER-334,” all availablefrom Dow Chemical Co., Midland, Mich. Other suitable epoxy resinsinclude glycidyl ethers of phenol formaldehyde novolac (e.g., “DEN-431”and “DEN-438” available from Dow Chemical Co., Midland, Mich.). Otherepoxy resins include those described in U.S. Pat. No. 4,751,138 (Tumeyet al.).

[0040] Other suitable adhesives include waterborne acrylic polymers orcopolymers, commercially available under the trade designation NEOCRYL;urethane-acrylic copolymers, commercially available under the tradedesignation NEOPAC; polyurethane resins, commercially available underthe trade designation NEOREZ, all available from Zeneca Division of ICIAmerica, Wilmington, Mass.; and acrylic and acrylonitrile latex resins,commercially available under the trade designation HYCAR, available fromB.F. Goodrich, Cleveland, Ohio. Still other suitable adhesives includeacrylated acrylic or acrylated urethane polymer resins, commerciallyavailable under the trade designation NEORAD, available from ZenecaDivision of ICI America, Wilmington, Mass.; acrylated polyester resins,commercially available under the trade designation IRR-114, availablefrom UCB Chemical Corp., Atlanta, Ga., and butadiene and butadienestyrene resins.

[0041] Further suitable adhesives include a 100% solids blend of vinylether monomers and oligomers. Such resins are typically low molecularweight materials which form films by crosslinking upon exposure to UVradiation. Examples of commercially available blends include RAPICUREfrom ISP, Wayne, N.J.; and VECTOMER from Allied Signal, Morristown, N.J.A catalyst is typically required to initiate crosslinking. A suitablecatalyst such as UVI-6990 (a cationic photocatalyst) from Union Carbide,Danbury, Conn., may be used.

[0042] Suitable urea-aldehyde resins include any urea or ureaderivatives and any aldehydes which are capable of being renderedcoatable and have the capability of reacting together at an acceleratedrate in the presence of a catalyst, preferably a cocatalyst.

[0043] Acrylate resins include both monomeric and polymeric compoundsthat contain atoms of carbon, hydrogen and oxygen, and optionally,nitrogen and the halogens. Oxygen or nitrogen atoms or both aregenerally present in ether, ester, urethane, amide, and urea groups.Representative examples of acrylate resins include methylacrylate,ethylacrylate, methyl methacrylate, ethyl methacrylate, ethylene glycoldiacrylate, ethylene glycol dimethacrylate, hexanediol diacrylate,triethylene glycol diacrylate, trimethylolpropane triacrylate, glyceroltriacrylate, pentaerythritol triacrylate, pentaerythritoltrimethacrylate, pentaerythritol tetraacrylate and pentaerythritoltetramethacrylate.

[0044] A hot melt resin may also be used. Exemplary hot melt resins aredescribed in U.S. Pat. No. 5,436,063 (Follett et al.). Hot melt resinsinclude compositions that are solid at room temperature (about 20-22°C.) but which, upon heating, melts to a viscous liquid that can bereadily applied to a backing. Useful hot melt resins includethermoplastics such as polyolefins, polyesters, nylons and ionomerresins (SURLYN from DuPont of Wilmington, Del.).

[0045] Other hot melt resins may include blends of thermoplastic resinswith thermosetting resins. Thermoplastic resins are typically suppliedas pellets and must be melted, pumped and extruded in hot form as asheet or film. The film can be applied directly to backings withnon-contact forming equipment (drop or extrusion dies, for example) orwith contact equipment (ROC or rotating rod dies). The extruded coatingcan be solidified by cooling or it can be crosslinked with ultraviolet(UV) energy if radiation curable components are present in the hot melt.It is also possible to provide the hot melt resins as uncured,unsupported rolls of adhesive film. In this instance, the resin isextruded, cast, or coated to form the film. Such films are useful intransfer coating the resin to a backing.

[0046]FIG. 6 is a partial cross-sectional view of a fourth embodiment ofa spiral belt 150 formed from a spiral wound abrasive media 155 havingthree overlapped webs: an outermost web 160, a middle web 170 and aninnermost web 180. Each web 160, 170, 180 is shown to be about equal inwidth 162, with each web 160, 170, 180 offset from the adjacent web orwebs about one-half the width 162. As a result, the middle web 170 has aone-half width exposed portion 171 and the innermost web 180 has aone-half width exposed portion 181. As the abrasive media 155 winds toform the spiral belt 150, the first web 160 overlaps the exposed portion171 of the middle web 170, and the middle web 170 overlaps the exposedportion 181 of the innermost web 180, such that each web 160, 170, 180produces abutting joints with no appreciable gap. Although fourembodiments have been shown and described, it is to be understood thatother web configurations for the abrasive media are possible and withinthe contemplation and scope of the present invention. In addition,although adhesive is described herein as preferred for attachment of theoverlapped webs, it is to be understood that other forms of attachmentmay also be used are and within the scope of the present invention.

[0047] As shown, the abrasive media 80, 80′, 122 and 155 are preferablyconfigured as a plurality of webs positioned in an adjacent andoverlapping manner with respect to each other. The first or outermostwebs 50, 50′, 125, 160 are preferably coated abrasives formed from oneor more layers of material and one or more layers of abrasive particles.Coated abrasives generally comprise a flexible backing upon which abinder supports a coating of abrasive particles. The abrasive particlesare typically secured to the backing by a first binder, commonlyreferred to as a make coat. Additionally, the abrasive particles aregenerally oriented with their longest dimension perpendicular to thebacking to provide an optimum cut rate. A second binder, commonlyreferred to as a size coat, is then applied over the make coat and theabrasive particles to further anchor the particles to the backing so asto reduce the likelihood of minerals fracturing off during use.

[0048] Porous cloth, fabric and textile materials are frequently used asbackings for coated abrasive articles. The make coat precursor istypically applied to the backing as a low viscosity material. In thiscondition, the make coat precursor can infiltrate into the intersticesof the porous backing leaving an insufficient coating thickness makingit difficult to bond the subsequently applied abrasive particles to thebacking and, on curing, resulting in the backing becoming stiff, hardand brittle. As a result, it has become conventional to employ one ormore treatment coats, such as a presize, saturant coat, backsize or asubsize coat, to seal the porous backing. Such treatment coats alsoallow for the use of less expensive backing materials, such as paper,combined with reinforcing materials, as described below, to achievesimilar strength and tear resistance as that of more expensive clothtype backings.

[0049] The presize, saturant coat, backsize and subsize coat typicallyinvolve thermally curable resinous adhesives, such as phenolic resins,epoxy resins, acrylate resins, acrylic lattices, lattices, urethaneresins, glue, starch and combinations thereof. A saturant coat saturatesthe cloth and fills pores, resulting in a less porous, stiffer clothwith more body. An increase in body provides an increase in strength anddurability of the article. A presize coat, which is applied to the frontside of the backing, may add bulk to the cloth or may improve adhesionof subsequent coatings, or may act as a barrier to excessive make coatpenetration. A backsize coat, which is applied to the back side of thebacking, i.e., the side opposite that to which the abrasive grains areapplied, adds body to the backing and protects the yarns of the clothfrom wear. A subsize coat is similar to a saturation coat except that itis applied to a previously treated backing. The drawback of such apresize, saturant coat, backsize and subsize coat is that it entailsadded processing step(s) which increase the cost and complexity ofmanufacturing. Similarly, paper backings may be treated to preventpenetration of make adhesives and/or to waterproof.

[0050] As described above, a backing may be a conventional, sealedcoated abrasive backing or a porous, non-sealed backing. Such a backingmay be comprised of cloth, vulcanized fiber, paper, nonwoven materials,fibrous reinforced thermoplastic backing, polymeric films, substratescontaining hooked stems, looped fabrics, metal foils, mesh, foambackings, and laminated multilayer combinations thereof. Cloth backingscan be untreated, saturated, presized, backsized, porous, or sealed, andthey may be woven or stitch bonded. The cloth backings may includefibers or yarns of cotton, polyester, rayon, silk, nylon or blendsthereof. The cloth backings can be provided as laminates with differentbacking materials described herein. Paper backings also can besaturated, barrier coated, presized, backsized, untreated, orfiber-reinforced. The paper backings also can be provided as laminateswith a different type of backing material. Nonwoven backings includescrims and may be laminated to different backing materials mentionedherein. The nonwovens may be formed of cellulosic fibers, syntheticfibers or blends thereof. Polymeric backings include polyolefin orpolyester films, nylon, SURLYN ionomer or other materials that may behot-melt laminated. The polymeric backings can be provided as blownfilm, or as laminates of different types of polymeric materials, orlaminates of polymeric films with a non-polymeric type of backingmaterial. The backing can also be a stem web used alone or incorporatinga nonwoven, or as a laminate with a different type of backing. The loopfabric backing can be brushed nylon, brushed polyester, polyesterstitched loop, and loop material laminated to a different type ofbacking material. The foam backing may be a natural sponge material orpolyurethane foam and the like. The foam backing also can be laminatedto a different type of backing material. The mesh backings can be madeof polymeric or metal open-weave scrims. Additionally, the backing maybe a reinforced thermoplastic backing that is disclosed in U.S. Pat. No.5,417,726 (Stout et al.).

[0051] An additional benefit of the processes and constructionsdescribed in this invention is shape retention. After conventionalconverting processes, coated abrasive belts and disks may change shapeor “cup” by as much as 2 inches depending upon the environment ofstorage conditions for these products. These types of changes aretypically caused by the different web components in such productspicking up environmental moisture or humidity at different rates. Thepresent spiral process of this invention has flexibility to allow themoisture sensitive web components (typically paper) to be covered orprotected from moist or humid air. For example in one embodiment of thisinvention, a polyester film adhesive carrier also serves as a moisturebarrier. The prevention of cupping over a wide range of relativehumidity removes the necessity of further treating these types ofproducts in order to meet acceptability requirements.”

[0052] In the first embodiment, the first web 50 is preferably a coatedabrasive that may be formed from one or more layers of abrasiveparticles and one or more layers of backing material. The second web 60is preferably a splicing media formed from one or more layers of filmcoated on at least one side with an adhesive, such as an adhesivepolymeric tape, or a coated fabric. The adhesive may be a pressuresensitive adhesive or PSA requiring little or no processing aftercontact. Alternatively, the adhesive may require thermal or radiationcuring to fully complete adhesion between the webs 50, 60. The film maybe a polymer film, such as a 0.5 mil polyester film, or a fiberreinforced film.

[0053] In the second embodiment, the first web 50′ is also preferably acoated abrasive. The second web 60′ is preferably a reinforcing backing,as described above, that may be attached to the first web 50′ using oneof a variety of techniques know in the industry. The area of adhesive onthe offset portion 66′ may be applied to either the first or second webs50′, 60′, respectively, after attachment of the second web 60′ or may beapplied during such attachment.

[0054] In the third embodiment, the first web 125 is also preferably acoated abrasive and the second web 130 is preferably a reinforcingbacking. The third web 135 is preferably a splicing media, as describedabove for the first embodiment. Both the second and third webs 130, 135may be attached to the first web 125 using one or more known techniques,with the adhesive on the offset portion 136 applied during or afterattachment of the webs 130, 135.

[0055] In the fourth embodiment, the outermost web 160 may also be acoated abrasive, with the middle web 170 a reinforcing material and theinnermost web 180 a splicing media or other suitable joining material.Alternatively, the outermost web 160 is preferably the topmost layer ofa coated abrasive, such as an abrasive coated backing material formedfrom a cloth or paper. However, the outermost web 160 may also includemultiple layers of abrasive particles and/or multiple layers of backingmaterial, if desired. The innermost web 180 is preferably the lowermostlayer of the coated abrasive, such as a reinforcing material, includinga nonwoven or other suitable material that provides strength to thespiral belt 150 without providing a substantial increase in weight.Alternatively, the innermost web 180 may be a hook-and-loop material,foam or other material described above for use as a backing. Optionally,the innermost web 180 may also be multiple layers if desired.

[0056] The middle web 170 is preferably an adhesive layer that joins theother layers of the coated abrasive forming the abrasive media 155. Inone embodiment, the adhesive layer is formed from adhesive materialcoated onto both surfaces of a film layer. For example, ethylene acrylicacid, sold as SCOTCHPACK from 3M Company in St. Paul, Minn., is coatedon both sides of a 0.5 mil polyester film to form a total layerthickness of 3.5 mil. After the webs 160, 170, 180 are brought together,heat (at a temperature in the range of about 260-270° F. to achieve thecure temperature of the adhesive) and pressure are applied to theoverlapped portions to activate crosslinking and bond the webs 160, 170,180 together.

[0057] In another example, an ultraviolet (UV) curable resin is coatedonto both surfaces of a polyester film layer to form the middle web 170.One formulation of this resin includes 70 parts EPON 828 (epoxy), 30parts HYTREL 6356 (polyester thermoplastic resin) and 1.5 parts CYRACUREUVI-6974 (triarylsulfonium salt photocatalyst). The mixture is heated to125-130° C. before being applied to the film. The adhesive is thenpreferably tackified with UV energy by passing it once beneath a 600watt/inch Fusion lamp using a D-bulb, a medium pressure, mercury vaporlamp as described by Fusion Systems, Inc., just prior to winding of thespiral belt. Once the middle adhesive layer is tackified, the spiralbelt 150 is formed from the three web layers 160, 170, 180. After beltformation, the belt 150 is heated for five minutes at 125° C. tocomplete the adhesive cure.

[0058] In yet another embodiment, the middle web 170 may be formed froman adhesive layer configured as a pre-cast film of adhesive material.Such adhesives may include SURLYN ionomer, a Zn-modifiedethylene/methacrylic acid copolymer by DuPont.

[0059] In the first embodiment, the coated abrasive first web 50 isformed in one or more processes, the second web 60 splicing media iscoated with adhesive and attached to the first web 50 along an edge 52,54 and then the combined abrasive media 80 is wound to form the spiralbelt 100. In a similar manner in the second and third embodiments, thecoated abrasive first web 50′, 125 is formed in one or more processes,the second reinforcing web 60′, 130 is formed in one or more processes,and then the second web 60′, 130 is attached to the first web 50′, 125.In the second embodiment, the combined abrasive media 80′ is thenspirally wound to form the belt 100′. In the third embodiment, the thirdweb 135 is formed in one or more processes, an adhesive is applied, andthe third web 135 is attached to the first web 125. Afterward, thecombined abrasive media 122 is spirally wound to form the belt 120. Inthe fourth embodiment, on the other hand, the formation of the abrasivemedia 155 preferably occurs simultaneously with the winding andformation of the spiral belt 150, thereby eliminating numerousprocessing steps, as well as the need for a splicing media, such as web60 in the first embodiment or web 135 in the third embodiment. Suchsimultaneous formation also ensures both a good lamination of theabrasive media 155 and a strongly joined belt 150.

[0060] Formation of the spiral belt 100, 100′, 120, 150 from the spiralwound abrasive media 80, 80′, 122, 155 may be accomplished in numerousways. FIGS. 7 and 8 show one embodiment of a spiral wound abrasive beltformation apparatus 200 configured to accept an input abrasive media 210formed from a first web 212 and a second splicing web 214. The apparatus200 includes a convexly curved hub 220 over which the abrasive media 210is draped during the winding process. The hub 220 is supported by theapparatus 200 in a cantilevered manner to allow for continuous formationof a spiral belt 215 of ever increasing width having a spiral seam 216formed where the edges of the first web 212 abut.

[0061] The apparatus 200 also includes a base 202 that supports the hub220 and a ‘C’ shaped arm 230. The arm 230 extends out both above andbelow a portion of the hub 220 and is mounted for pivotal movement withrespect to the base 202. At the furthermost upper end 231 of the arm 230two upper press rollers 235, 236 are mounted for pressure contact withtwo corresponding lower press rollers 237 that are mounted to thefurthermost lower end 232 of the arm 230. An opening 222 formed in thehub 220 adjacent the press rollers 235, 236, 237 allows for contactbetween the upper press rollers 235, 236 and lower press rollers 237. Asthe abrasive media 210 passes between the upper and lower press rollers235, 236, 237, pressure is applied to both the upper and lower surfacesof the seam 216. Mounted on the underside 221 of the hub 220 adjacentthe lower press rollers 237 is an optional heating element 223positioned to radiate heat to the abrasive media 210. Optionally, alight source (not shown) may also be mounted on the underside 221 of thehub 220 at the opening 222 to shine up through seam 216 and thus aid inminimizing gaps at the seam 216.

[0062] One of the upper press rollers 235 is configured to be manuallydriven by rotary mechanism 233. As the abrasive media 210 is fed intothe apparatus 200, the rotary mechanism 233 is turned to rotate thedriven press roller 235 and thus pull the abrasive media 210 through theapparatus. In this embodiment, the remainder of the press rollers 236,237 are not driven. Although configured with a manual drive, it is to beunderstood that the apparatus 200 may alternatively be configured with apowered drive, with or without control.

[0063] The apparatus 200 also includes a guide tray 225. The guide tray225 is adjustably mounted to support the input abrasive media 210 at adesired height and angle with respect to the hub 220.

[0064] Prior to input into the apparatus 200, the abrasive media 210 isconstructed from webs 212 and 214. An angled leading edge or end 211 maybe pre-cut into the abrasive media 210.

[0065] The apparatus 200 is then set up to form a spiral belt 215 havinga desired width and circumference from pre-constructed abrasive media210. The angle of the guide tray 225 with respect to the hub 220establishes the angle at which the spiral belt 215 is wound and, thus,the size of the belt 215. Therefore during set up, the guide tray 225 ispositioned at a desired angle with respect to the hub 220. The pressrollers 235, 236, 237 facilitate joining of the first web 212 to thesecond web 214 by providing pressure to the abrasive media 210 as theseam 216 is formed. Therefore, during set up, the arm 230 is alsopivoted to position the press rollers 235, 236, 237 at the desired angleto follow the abrasive media 210 as it is input from the guide tray 225.In addition, the pressure exerted by the upper press rollers 235, 236against the lower press rollers 237 may be adjusted based on therequirements of the abrasive media 210 forming the spiral belt 215, andheat to soften or cure the adhesive may be supplied as needed fromoptional heater 223.

[0066] In operation, the abrasive media 210 is fed into the apparatus200 along the guide tray 225 and over the hub 220. The leading end oredge 211 is wrapped around the hub 220 and is fed back into theapparatus 200 at the press rollers 235, 236, 237 to start formation ofthe seam 216 and, thus, the spiral belt 215. Preferably, a firstoperator feeds the abrasive media 210 into the apparatus 200 whilemonitoring and attempting to minimize any gap at the seam 216. A secondoperator manually drives the driven press roller 235 using the rotatingmechanism 233, thereby continuously feeding the abrasive media 210 intothe apparatus and applying pressure at the press rollers 235, 236 237 tothe first web 212 as it overlaps the second web 214 at the seam 216 tobond the webs 212, 214 together. Heat may also be provided by theoptional heater 222, if available and desired, to facilitate bonding ofthe webs 212, 214. The abrasive media 210 continues to be fed into theapparatus 200 and wrapped over the hub 220 forming the spiral belt 215until a spiral belt 215 of desired width has been formed or until asecond end (not shown) of the abrasive media 210 is reached. Once thespiral belt 215 is completed, tabs (such as tabs 109 in FIG. 1) may beapplied to maintain adherence of the abrasive media 210 at both ends.

[0067]FIG. 9 shows another embodiment of a spiral wound abrasive beltformation apparatus 300 configured to accept a plurality of webs, suchas webs 312, 313, 314, that simultaneously form the abrasive media 310and the spiral belt 315. It is to be understood, however, that more orless webs may be used to form the abrasive media and spiral belt, ifdesired. As described above, the outermost web 312 is preferably acoated abrasive, the middle web 313 is preferably an adhesive layer, andthe innermost web 314 is preferably a reinforcing layer. The three webs312, 313, 314 are wound over a stationary first hub 320 mounted to afirst support system 322 in a cantilevered manner.

[0068] The three webs 312, 313, 314 are presented at an angle 318relative to the first hub 320. The angle 318 may be adjusted toaccommodate different dimensions of the webs 312, 313, 314 and thespiral belt 315. A web steering system including a steering roller (notshown) or other suitable device may be included to control thepresentation of one or more of the webs. The webs 312, 313, 314 are alsopresented to be partially overlapping, such that during winding of thespiral belt 315, each web's edges abut, preferably without appreciablegaps, forming three relatively continuous layers (see the fourth spiralbelt embodiment in FIG. 6).

[0069] The splice angle of the spiral webs may be controlled by thewidth of the input rolls of the abrasive web or materials in order toprovide preferred non-marking properties. For example, in a 52 inch×103inch belt, the typical splice angle is 71°, when the splice is made withthe use of conventional belt cutting devices and belt presses. With thespiral belt process, and using a 12 inch wide input roll, the spliceangle of the spiral wrap would be 6.7°. Smaller splice angles arepreferred by customers where splice marking and loading are generallythe normal useful life endpoints of the abrasive belt. The splice anglemay also be controlled by selecting different widths of input rolls ofabrasive web. For example, for a 52 inch×103 inch belt, the splice anglemay be adjusted from 6.7-20.5° by varying the width of the input rollsfrom 12 inches to 36 inches.

[0070] After passing over the first hub 320, the abrasive media 310passes around a second hub 325 moveably mounted to a second supportsystem 327. The second hub 325 maintains the spiral belt 315 in tensionand is adjustable toward and away from the first hub 320 in order toaccommodate a wide range of spiral belt circumferences. The second hub325 is also preferably configured as a drive roller that automaticallyfeeds the abrasive media 310 to continuously form the abrasive media 310and spiral belt 315 from the webs 312, 313, 314.

[0071] As the spiral belt 315 is formed, the spiral belt width 316continues to increase. In this embodiment, a belt cart 330 is providedto accept the formed spiral belt 315 from the apparatus 300 and supportthe widening spiral belt 315. The belt cart 330 includes a first beltsupport 332 set at a height equivalent to the height of the first hub320. Also included on the cart 330 is a second belt support 334 moveablymounted, such that it may be adjusted to a height equivalent to that ofthe second hub 325. The belt cart 330 also includes casters 335, orother mechanism for moving the cart 330 toward and away from theapparatus 300 to accommodate the changing width 316 of the belt 315.

[0072]FIG. 10 is a diagram of yet another embodiment of a spiral woundabrasive belt winding apparatus 400 configured to accept a plurality ofwebs, such as webs 412, 413, 414, that simultaneously form an abrasivemedia 410 and a spiral belt 415. As described above, the outermost web412 is preferably a coated abrasive, the middle web 413 is preferably anadhesive layer, and the innermost web 414 is preferably a reinforcinglayer, however other numbers and types of webs may also be used. Thethree webs 412, 413, 414 are wound over a stationary first hub 420 thatis mounted in a cantilevered manner. A moveably mounted second hub 425provides tension for the spiral belt 415 and adjusts to accommodatespiral belts 415 of varying circumferences, as shown by phantom secondhub 426 and belt 416.

[0073] In this embodiment, a pair of driven nip rollers 430 drives theabrasive media 410 in a winding spiral to form the spiral belt 415 andapplies pressure to the abrasive media 410 to assist adhesion betweenthe webs 412, 413, 414. The position and angle of the nip rollers 430with respect to the abrasive media 410 may be adjusted to accommodatechanges in the abrasive media 410 due to adjustment of the second hub425, adjustments of the input angle of the webs 412, 413, 414, or otherfactors.

[0074] Significant gaps or web overlap at the spiral seam (not shown) ofthe spiral belt 415 will cause surface marks and other surfacenon-conformities in an item ground or polished by the spiral belt 415 ina subsequent operation. Therefore, minimization of gaps or overlap isnecessary to provide an acceptable spiral belt 415. The apparatus 400includes one embodiment of a gap minimization system 440 to monitor thespiral seam and correct unacceptable seam separation.

[0075] The gap minimization system 440 includes a sensing mechanism 445that uses a light source 446 positioned on the outermost web 412 side ofthe abrasive media 410 at a point 448 where the outermost web 412attaches to the middle web 413. The light source 446 may be visiblelight or may be infrared light, if desired. A light sensor 447 ispositioned at the same point, but on side of the first hub 420 oppositethe abrasive media 410. The light sensor 447 senses the amount of lightshining through the gap at the seam of the outermost web 412. Acontroller 450 monitors the light sensor 447 and controls a positioningsystem 452 that adjusts the position of the outermost web 412 relativeto the spiral belt 415, thereby adjusting the gap. The positioningsystem 452 includes a positioning motor 452 connected to the controller450 and a web movement mechanism 453 driven by the positioning motor452. In order to better accommodate changes in the position of theoutermost web 412, a steering roller 445 is included to route theoutermost web 412 through the web movement mechanism 453. With such agap minimization system 440, the light source 446 should be strongenough to pass a small amount of light through an optimized seam so thatno light may be construed to be web overlap.

[0076] It is to be understood that other embodiments of a gapminimization system are possible and are within the spirit and scope ofthe present invention. For example, the visible light source 446 andlight sensor 447 may be switched such that the light shines up throughthe abrasive media 410, thereby allowing an operator to monitor thelight passing through the seam, as well. In addition, the web movementmechanism 453 may be only a push plate the can move the web in onedirection toward the spiral belt. In this situation, the outermost webshould be initially set up with a small amount of gap to allow for suchunidirectional adjustment.

[0077] Although the embodiments described above form a spiral abrasivebelt from abrasive media including a coated abrasive web, it is to beunderstood that such a spiral belt may also be formed from non-coatedabrasive media. The resulting spiral belt may then be used in operationsrequiring very light abrasion, such as the polishing or burnishing ofleather, for example. Alternatively, the resulting spiral belt may besubsequently coated on the outer surface with abrasive particles to forma spiral wound abrasive belt with a coated abrasive surface.

[0078] The present invention provides a spiral wound abrasive belt thatmay be formed in a continuous manner, may be formed in varyingcircumferences, and may be slit to a large range of widths, as needed.The spiral belt may be constructed from abrasive media whose edges arejoined together along a spiral seam, or may be constructed fromindividual webs that simultaneously form the abrasive media and thespiral belt. The webs used to construct the spiral belt may be chosen tooptimize the strength and durability of the belt, thus producingabrasive belts with significantly longer lives, while minimizing theweight and other belt characteristics that impact installation and useof the belt in subsequent abrasive applications.

[0079] The methods of forming spiral wound abrasive belts and theapparatuses for practicing these methods in accordance with the presentinvention result in reduced labor and material costs. The methods andmachines eliminate the need for multiple splices and custom sizedequipment to form belts having the necessary circumference and width fora specific application. In addition, the offset layer process andequipment eliminate the need for any additional joining material andallow for the inclusion of all layers of the abrasive media into thespiral belt construction.

EXAMPLES Example 1

[0080] A wide spiral wound abrasive belt that was about 1.32 meters (52inches) wide by about 2.62 meters (103 inches) in circumference, wasassembled using the apparatus 200, as shown in FIG. 7. The first web 212was about 0.305 meters (12 inches) in width and was a coated abrasiveformed from an outermost layer of 3M 961 UZ coated abrasive manufacturedby 3M Company of St. Paul, Minn., a paper coated with abrasiveparticles, a middle layer of SURLYN hot melt adhesive pre-cast film, andan innermost layer of a nonwoven material, CEREX 2320 (plain) and T70ORION fabric (DN style with diamond pattern), both fabricated by CerexAdvanced Fabrics of Pensacola, Fla., using a spunbond process. Both websmade from nylon fiber.

[0081] The second web 214 was a splicing material that was formed from a0.5 mil polyester film having a width of about 0.305 meters (12 inches).The film was top coated with UV-curable adhesive. Prior to winding ofthe spiral belt, the splicing material was attached to the underside ofthe coated abrasive web, that is to the nonwoven material, at one edgealong the length of the web, thereby forming the abrasive media 210.About one half of the width of the splicing material coated withadhesive was left exposed along the edge.

[0082] The abrasive media 210 was hand fed into the apparatus 200 andspirally wound about the hub 220 by a first operator. A second operatormanually drove the driven press roller 235, and the press rollers 235,236, 237 bonded the coated abrasive to the splicing media along thespiral seam 216. The resulting spiral abrasive belt was later evaluatedfor performance and reliability characteristics.

[0083] Although the present invention has been described with referenceto preferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. In addition, the invention is not to betaken as limited to all of the details thereof as modifications andvariations thereof may be made without departing from the spirit orscope of the invention.

What is claimed is:
 1. An apparatus for forming a spiral wound endlessabrasive article comprising: a hub supported in a cantileveredconfiguration, the hub having a longitudinal axis and a convex outersurface; a web feeder adapted to introduce a first web and a second webonto the hub at an angle relative to the axis of the hub, the first andsecond webs positioned in an offset and overlapping configuration; and aweb joiner adapted to join abutting edges of the first web by overlap ofthe second web as the first and second webs spirally wind about the hubto form a spiral wound article having a circumference greater than theouter surface of the hub.
 2. The apparatus of claim 1, wherein the firstweb and second web are adhered at the overlap of the first web and thesecond web.
 3. The apparatus of claim 1, wherein the web joinercomprises at least one press roller adjustably positioned adjacent theouter surface of the hub, the press roller configured to apply pressureto the first and second webs at the abutting edges of the first web asthe first and second webs pass under the press roller.
 4. The apparatusof claim 3, wherein the web joiner further comprises a plurality ofpress rollers, at least one of which is driven to move the first andsecond webs under the press rollers.
 5. The apparatus of claim 4,wherein the plurality of press rollers comprises two upper press rollersand two lower press rollers forming a nip through which the first andsecond webs pass.
 6. The apparatus of claim 3, wherein the web feedercomprises a guide adjustably positioned adjacent the hub outer surface,the guide configured to receive the first and second webs and positionthe first and second webs with the abutting edges of the first webbeneath the press roller as the first and second webs spirally windabout the hub.
 7. The apparatus of claim 1, wherein the web feeder isfurther adapted to introduce a third web on to the hub at the same anglerelative to the axis of the hub, the third web positioned in an offsetand overlapping configuration relative to the second web.
 8. Theapparatus of claim 7, wherein the web feeder comprises a plurality ofweb unwinds and a web steering mechanism for positioning at least one ofthe first, second and third webs at the desired angle relative to theaxis of the hub.
 9. The apparatus of claim 8, wherein the steeringmechanism comprises an adjustable web steering bar for positioning thefirst, second and third webs at the desired angle.
 10. The apparatus ofclaim 8, wherein the steering mechanism comprises an adjustable webguide that contacts the first web and adjusts the position and angle ofthe abutting edges of the first web relative to each other.
 11. Theapparatus of claim 10, wherein the steering mechanism further comprisesa sensor that senses incorrect positioning of the abutting edges of thefirst web.
 12. The apparatus of claim 11, wherein the sensor comprisesfeedback control connected to the web guide for automatic adjustment ofweb angle and position.
 13. The apparatus of claim 7, wherein the hubcomprises a first hub and wherein the apparatus further comprises asecond hub adjustably supported in a cantilevered configuration at adistance from the first hub, the webs passing around the second hubwhile spirally winding about the first hub to produce a spiral woundarticle having a desired circumference.
 14. The apparatus of claim 13,wherein the apparatus further comprises a web driving mechanism thatpulls the webs over the hub at the angle relative to the axis of thehub.
 15. The apparatus of claim 14, wherein the web driving mechanismcomprises a driven roller.
 16. The apparatus of claim 15, wherein thesecond hub comprises the driven roller.
 17. The apparatus of claim 14,wherein the web driving mechanism comprises driven nip rollers.
 18. Theapparatus of claim 7, wherein web joiner comprises a heated hub.
 19. Theapparatus of claim 7, wherein the first web comprises a coated abrasive,the second web comprises an adhesive material, and the third webcomprises a reinforcing material.
 20. The apparatus of claim 1, whereinthe first web comprises a coated abrasive and the second web comprises asplicing media.